Based on cockpit voice and flight data recorder information from the Air India Boeing 787-8 crashed in Ahmedabad on June 12, India's civil aviation regulator has released a preliminary report showing that both the jet's fuel cutoff switch had been reversed to the “cutoff” position just after takeoff.
India's Ministry of Civil Aviation said in a report on July 11th that “heard one of the pilots asking others why he cut off.”
“The other pilots replied that he didn't.”
Investigators say the aircraft reached an airspeed of 180kt at 08:08:42 local time after takeoff.
Next, the fuel cutoff switches for Engine 1 and Engine 2 shifted from “execution” to “cutoff” one after another with a gap of about a second.
Both GE Genx-1B turbofans began to “decrease from takeoff values” as fuel supply was cut off, the report says.
When both engines fell below the minimum idle speed, the aircraft's RAM air turbines (rats) began supplying hydroelectric power at 08:08:47.
According to flight data, the fuel cut switches on both engines then moved from “cutoff” to “run”, starting a learning and fuel introduction sequence for a fully-authorized dual engine control (FADEC) control engine.
“The core deceleration on Engine 1 has stopped, reversed and started moving towards recovery,” the report states. “The engine 2 was able to regenerate, but it was unable to repeatedly stop the core speed deceleration, and repeatedly reintroduced fuel to increase the acceleration and recovery of core speed.”
One of the pilots issued a desperate “Mayday” call at 08:09:05.
The report said Air Traffic Control “studyed about the call sign,” but there was no response. It was then observed that the 787-8 crashed outside the boundaries of the airport, and emergency response was activated.
Twinjet stayed high for about 30s before attacking medical school, erupting in a massive fireball, with 241 of the 242 on board.
Five buildings in the area suffered major fire damage.
Indian investigators say they have recovered both GE turbo fans from the remains isolated in a hangar at Ahmedabad airport.
“Factors of interest for further testing have been identified and quarantined,” he says.
In particular, investigators say the FAA issued a special Voyage Information Breaking News (SAIB) in December 2018 regarding the potential release of the fuel-controlled switch locking feature of the 737-Family jet.
“The design of fuel-controlled switches, including locking capabilities, is similar on various Boeing plane models,” they say. “According to information from Air India, the proposed inspection was not conducted as SAIB is a recommendation and is not required.”
The investigation is ongoing and involves from the US National Traffic Safety Commission, FAA, Boeing and GE Aerospace.
